Osteoarthritis is usually regarded as a non-inflammatory disease. However, several authors have stressed the importance of an inflammatory phase early in the development of the condition, and specific inflammatory types of osteoarthritis have been described. Comparative trials of pure analgesic and anti-inflammatory drugs in a small sub-group of these patients showed a similar reduction of pain with both types of agent. However, a significantly greater improvement in joint tenderness and stiffness was found during treatment with anti-inflammatory drugs.